Applied Microbial Ecology Research at UW-Madison

Photosynthesis + Wastewater

Microbes have been put to work in wastewater treatment for many years now. With their diverse range of metabolic processes and preferred living conditions, microbes are capable of removing many different types of compounds from our waste. Much of the research in the McMahon Lab focuses on polyphosphate accumulating organisms (PAOs), microbes that can take up and store phosphorus. To select for these organisms, a wastewater treatement process needs to alternate between aerobic (high oxygen) and anaerobic (low oxygen) conditions. However, this cycling can get expensive. That’s because we need to pump oxygen into the reactors, a process called “aeration.”

Wouldn’t it be great if there was a microbe that produced oxygen but only when you flipped on a switch? Look no further than photosynthesis, the process of producing sugar from sunlight. Photosynthetic bacteria and algae produce oxygen, but only when exposed to light. Combine this with phosphorus-storing bacteria, plus something to provide nitrogen from the wastewater (in this case, nitrifiers), and you’ve got a process that doesn’t need pumped oxygen!

Former lab member Ben Oyserman built just such a reactor as he was finishing up his PhD, and it’s pretty cool. For more info, check out his paper here.